The direct catalytic asymmetric aldolreaction offers efficient access to β‐hydroxy carbonyl entities. Described is a robust direct catalytic asymmetric aldolreaction of α‐sulfanyl 7‐azaindolinylamide, thus affording both aromatic and aliphatic β‐hydroxy amides with high ee values. The design of this transformation features a cooperative interplay of a soft and a hard Lewisacid, which together facilitate
A directcatalyticasymmetricaldolreaction of thioamides with a soft Lewis acid/hard Brønsted base cooperative catalytic system comprising (R,R)-Ph-BPE/[Cu(CH(3)CN)(4)]PF(6)/LiOAr is described. Highly chemoselective deprotonative activation of thioamides allows for a directaldolreaction of alpha-nonbranched aliphatic aldehydes, which are susceptible to self-condensation. Facile reduction of the
Highly Selective Acetate Aldol Additions Using Mesityl-Substituted Chiral Auxiliaries
作者:Michael T. Crimmins、Mariam Shamszad
DOI:10.1021/ol062688b
日期:2007.1.1
Highly diastereoselective acetate aldol additions using chlorotitanium enolates of mesityl-substituted N-acetyloxazolidinethione and N-acetylthiazolidinethione auxiliaries are reported. These additions proceed in high yields and diastereoselectivities (93:7 to 98:2) for aliphatic, aromatic, and alpha,beta-unsaturated aldehydes. Double diastereoselective acetate aldol additions are also reported and are found to proceed in high yields and diastereoselectivities (90:10 to 97:3).
Direct Catalytic Enantio- and Diastereoselective Aldol Reaction of Thioamides
under conventional basic conditions. A hard Lewis basic phosphine oxide has emerged as an effective additive to constitute a highly active ternary soft Lewisacid/hard Brønsted base/hard Lewis base cooperative catalyst, enabling a direct enantio- and diastereoselective aldol reaction of thiopropionamides. Strict control of the amount of the hard Lewis base was essential to drive the catalytic cycle